From patchwork Wed Jul 7 18:36:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brijesh Singh X-Patchwork-Id: 470858 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, MSGID_FROM_MTA_HEADER, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51EADC11F66 for ; Wed, 7 Jul 2021 18:40:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B9B261C98 for ; Wed, 7 Jul 2021 18:40:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233136AbhGGSnB (ORCPT ); Wed, 7 Jul 2021 14:43:01 -0400 Received: from mail-mw2nam10on2050.outbound.protection.outlook.com ([40.107.94.50]:61152 "EHLO NAM10-MW2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S232921AbhGGSlt (ORCPT ); Wed, 7 Jul 2021 14:41:49 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=DG6vcA01wDCi5xZwwzt0W7QowCCuFFNCCQXJPYnhYrQpO2MH6C9eP53EKd5I6PNf3LKars3efWe4VTuQtS/8nYVOC//+rsM6fxv2V/TMDTWjWD3m60eI92nyEC+cmMzdDlzjkvXPyUQT3h9c040ezOdTsBqSzdQFsYddvjpn9Pam0aaadADvBt0+zaPMNLuF0aRk8MkN0VZJfffl7EHVBiCe/UyogXjHDFHAn2PaZ+SP7w4STCNT38JoquHq2/dyh3N40z0MqdMKLfvSUfpAhVyen4ZfUyiWtQsQ2mC8io+uDWhZY7nxLfpHdae5UKry5S4DQMKIc2EoU1pVH1CjiQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=n3ig/SjWmQav36LO/5124ek20xvq0ll+4Y9DKzjMrzk=; b=Lc0Fx8OeEs0XuUX8XUBrpskfuvjdYIey0GmK4b5IIOjHPMmd7euVZBMT313H0dr21KPUhItRchCgZD33hZPpokyosHosKTA7J1uRZSh9QpiNKo1RL2xGoT3jHLCRaFqIJQvJxTeAD1tnjmn7JOs4Cn10uTAAW7zm+yUxTufFs2gCv0GRXNmC1NtCkmq6L1aCOQhcnssCTv59/oVzs3GgVwc3bVULgkvMaOwMeWfrRnELZq0F+OseWUX5gTYePhyTfH8IFKQtJJ0gun3CZkRmTSDtAJXDPQK8HxHLfl70Guv69Cg+EJomMPPKImXUQtW99jiz8Q38nglya8DCZggCVQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=n3ig/SjWmQav36LO/5124ek20xvq0ll+4Y9DKzjMrzk=; b=5Qq4k1B9CFIkcUxkg3LmXF6xxx/BYL5e2zSSBHr9ZfXBPo034tB/XI0rTuaLSGSyNnGkohSZVmx+od0t4HGPriqvgeF7if675PdNdO3AbO3RFtkVXAja8b4ZD5pPTfqW5gf4I1THY+T+fg94ax7mKlK/kpJQXjFoAd6OaAZEpvA= Authentication-Results: kernel.org; dkim=none (message not signed) header.d=none; kernel.org; dmarc=none action=none header.from=amd.com; Received: from BYAPR12MB2711.namprd12.prod.outlook.com (2603:10b6:a03:63::10) by BY5PR12MB4099.namprd12.prod.outlook.com (2603:10b6:a03:20f::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.20; Wed, 7 Jul 2021 18:38:25 +0000 Received: from BYAPR12MB2711.namprd12.prod.outlook.com ([fe80::40e3:aade:9549:4bed]) by BYAPR12MB2711.namprd12.prod.outlook.com ([fe80::40e3:aade:9549:4bed%7]) with mapi id 15.20.4287.033; Wed, 7 Jul 2021 18:38:25 +0000 From: Brijesh Singh To: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org Cc: Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , tony.luck@intel.com, npmccallum@redhat.com, brijesh.ksingh@gmail.com, Brijesh Singh Subject: [PATCH Part2 RFC v4 35/40] KVM: Add arch hooks to track the host write to guest memory Date: Wed, 7 Jul 2021 13:36:11 -0500 Message-Id: <20210707183616.5620-36-brijesh.singh@amd.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210707183616.5620-1-brijesh.singh@amd.com> References: <20210707183616.5620-1-brijesh.singh@amd.com> X-ClientProxiedBy: SN6PR04CA0078.namprd04.prod.outlook.com (2603:10b6:805:f2::19) To BYAPR12MB2711.namprd12.prod.outlook.com (2603:10b6:a03:63::10) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from sbrijesh-desktop.amd.com (165.204.77.1) by SN6PR04CA0078.namprd04.prod.outlook.com (2603:10b6:805:f2::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.20 via Frontend Transport; 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The kvm_vcpu_map() and kvm_map_gfn() are used by the hypervisor to map the guest memory and and access it later. When SEV-SNP is enabled in the guest VM, the guest memory pages can either be a private or shared. A write from the hypervisor goes through the RMP checks. If hardware sees that hypervisor is attempting to write to a guest private page, then it triggers an RMP violation (i.e, #PF with RMP bit set). Enhance the KVM guest write helpers to invoke an architecture specific hooks (kvm_arch_write_gfn_{begin,end}) to track the write access from the hypervisor. When SEV-SNP is enabled, the guest uses the PAGE_STATE vmgexit to ask the hypervisor to change the page state from shared to private or vice versa. While changing the page state to private, use the kvm_host_write_track_is_active() to check whether the page is being tracked for the host write access (i.e either mapped or kvm_write_guest is in progress). If its tracked, then do not change the page state. Signed-off-by: Brijesh Singh --- arch/x86/include/asm/kvm_host.h | 6 +++ arch/x86/kvm/svm/sev.c | 51 +++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 2 + arch/x86/kvm/svm/svm.h | 1 + arch/x86/kvm/x86.c | 78 +++++++++++++++++++++++++++++++++ include/linux/kvm_host.h | 3 ++ virt/kvm/kvm_main.c | 21 +++++++-- 7 files changed, 159 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 59185b6bc82a..678992e9966a 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -865,10 +865,13 @@ struct kvm_lpage_info { int disallow_lpage; }; +bool kvm_host_write_track_is_active(struct kvm *kvm, gfn_t gfn); + struct kvm_arch_memory_slot { struct kvm_rmap_head *rmap[KVM_NR_PAGE_SIZES]; struct kvm_lpage_info *lpage_info[KVM_NR_PAGE_SIZES - 1]; unsigned short *gfn_track[KVM_PAGE_TRACK_MAX]; + unsigned short *host_write_track[KVM_PAGE_TRACK_MAX]; }; /* @@ -1393,6 +1396,9 @@ struct kvm_x86_ops { void (*vcpu_deliver_sipi_vector)(struct kvm_vcpu *vcpu, u8 vector); void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu); int (*get_tdp_max_page_level)(struct kvm_vcpu *vcpu, gpa_t gpa, int max_level); + + void (*write_page_begin)(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn); + void (*write_page_end)(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn); }; struct kvm_x86_nested_ops { diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 0155d9b3127d..839cf321c6dd 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2884,6 +2884,19 @@ static int snp_make_page_shared(struct kvm_vcpu *vcpu, gpa_t gpa, kvm_pfn_t pfn, return rmpupdate(pfn_to_page(pfn), &val); } +static inline bool kvm_host_write_track_gpa_range_is_active(struct kvm *kvm, + gpa_t start, gpa_t end) +{ + while (start < end) { + if (kvm_host_write_track_is_active(kvm, gpa_to_gfn(start))) + return 1; + + start += PAGE_SIZE; + } + + return false; +} + static int snp_make_page_private(struct kvm_vcpu *vcpu, gpa_t gpa, kvm_pfn_t pfn, int level) { struct kvm_sev_info *sev = &to_kvm_svm(vcpu->kvm)->sev_info; @@ -2895,6 +2908,14 @@ static int snp_make_page_private(struct kvm_vcpu *vcpu, gpa_t gpa, kvm_pfn_t pfn if (!e) return -EINVAL; + /* + * If the GPA is tracked for the write access then do not change the + * page state from shared to private. + */ + if (kvm_host_write_track_gpa_range_is_active(vcpu->kvm, + gpa, gpa + page_level_size(level))) + return -EBUSY; + /* Log if the entry is validated */ if (rmpentry_validated(e)) pr_warn_ratelimited("Asked to make a pre-validated gpa %llx private\n", gpa); @@ -3468,3 +3489,33 @@ int sev_get_tdp_max_page_level(struct kvm_vcpu *vcpu, gpa_t gpa, int max_level) return min_t(uint32_t, level, max_level); } + +void sev_snp_write_page_begin(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn) +{ + struct rmpentry *e; + int level, rc; + kvm_pfn_t pfn; + + if (!sev_snp_guest(kvm)) + return; + + pfn = gfn_to_pfn(kvm, gfn); + if (is_error_noslot_pfn(pfn)) + return; + + e = snp_lookup_page_in_rmptable(pfn_to_page(pfn), &level); + if (unlikely(!e)) + return; + + /* + * A hypervisor should never write to the guest private page. A write to the + * guest private will cause an RMP violation. If the guest page is private, + * then make it shared. + */ + if (rmpentry_assigned(e)) { + pr_err("SEV-SNP: write to guest private gfn %llx\n", gfn); + rc = snp_make_page_shared(kvm_get_vcpu(kvm, 0), + gfn << PAGE_SHIFT, pfn, PG_LEVEL_4K); + BUG_ON(rc != 0); + } +} diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 2632eae52aa3..4ff6fc86dd18 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4577,6 +4577,8 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { .alloc_apic_backing_page = svm_alloc_apic_backing_page, .get_tdp_max_page_level = sev_get_tdp_max_page_level, + + .write_page_begin = sev_snp_write_page_begin, }; static struct kvm_x86_init_ops svm_init_ops __initdata = { diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index af4cce39b30f..e0276ad8a1ae 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -576,6 +576,7 @@ void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu); void sev_es_unmap_ghcb(struct vcpu_svm *svm); struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); int sev_get_tdp_max_page_level(struct kvm_vcpu *vcpu, gpa_t gpa, int max_level); +void sev_snp_write_page_begin(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn); /* vmenter.S */ diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bbc4e04e67ad..1398b8021982 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9076,6 +9076,48 @@ void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD); } +static void update_gfn_track(struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode, short count) +{ + int index, val; + + index = gfn_to_index(gfn, slot->base_gfn, PG_LEVEL_4K); + + val = slot->arch.host_write_track[mode][index]; + + if (WARN_ON(val + count < 0 || val + count > USHRT_MAX)) + return; + + slot->arch.host_write_track[mode][index] += count; +} + +bool kvm_host_write_track_is_active(struct kvm *kvm, gfn_t gfn) +{ + struct kvm_memory_slot *slot; + int index; + + slot = gfn_to_memslot(kvm, gfn); + if (!slot) + return false; + + index = gfn_to_index(gfn, slot->base_gfn, PG_LEVEL_4K); + return !!READ_ONCE(slot->arch.host_write_track[KVM_PAGE_TRACK_WRITE][index]); +} +EXPORT_SYMBOL_GPL(kvm_host_write_track_is_active); + +void kvm_arch_write_gfn_begin(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn) +{ + update_gfn_track(slot, gfn, KVM_PAGE_TRACK_WRITE, 1); + + if (kvm_x86_ops.write_page_begin) + kvm_x86_ops.write_page_begin(kvm, slot, gfn); +} + +void kvm_arch_write_gfn_end(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn) +{ + update_gfn_track(slot, gfn, KVM_PAGE_TRACK_WRITE, -1); +} + void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu) { if (!lapic_in_kernel(vcpu)) @@ -10896,6 +10938,36 @@ void kvm_arch_destroy_vm(struct kvm *kvm) kvm_hv_destroy_vm(kvm); } +static void kvm_write_page_track_free_memslot(struct kvm_memory_slot *slot) +{ + int i; + + for (i = 0; i < KVM_PAGE_TRACK_MAX; i++) { + kvfree(slot->arch.host_write_track[i]); + slot->arch.host_write_track[i] = NULL; + } +} + +static int kvm_write_page_track_create_memslot(struct kvm_memory_slot *slot, + unsigned long npages) +{ + int i; + + for (i = 0; i < KVM_PAGE_TRACK_MAX; i++) { + slot->arch.host_write_track[i] = + kvcalloc(npages, sizeof(*slot->arch.host_write_track[i]), + GFP_KERNEL_ACCOUNT); + if (!slot->arch.host_write_track[i]) + goto track_free; + } + + return 0; + +track_free: + kvm_write_page_track_free_memslot(slot); + return -ENOMEM; +} + void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) { int i; @@ -10969,8 +11041,14 @@ static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot, if (kvm_page_track_create_memslot(slot, npages)) goto out_free; + if (kvm_write_page_track_create_memslot(slot, npages)) + goto e_free_page_track; + return 0; +e_free_page_track: + kvm_page_track_free_memslot(slot); + out_free: for (i = 0; i < KVM_NR_PAGE_SIZES; ++i) { kvfree(slot->arch.rmap[i]); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 2f34487e21f2..f22e22cd2179 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1550,6 +1550,9 @@ static inline long kvm_arch_vcpu_async_ioctl(struct file *filp, void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, unsigned long start, unsigned long end); +void kvm_arch_write_gfn_begin(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn); +void kvm_arch_write_gfn_end(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn); + #ifdef CONFIG_HAVE_KVM_VCPU_RUN_PID_CHANGE int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu); #else diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 6b4feb92dc79..bc805c15d0de 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -160,6 +160,14 @@ __weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, { } +__weak void kvm_arch_write_gfn_begin(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn) +{ +} + +__weak void kvm_arch_write_gfn_end(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn) +{ +} + bool kvm_is_zone_device_pfn(kvm_pfn_t pfn) { /* @@ -2309,7 +2317,8 @@ static void kvm_cache_gfn_to_pfn(struct kvm_memory_slot *slot, gfn_t gfn, cache->generation = gen; } -static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn, +static int __kvm_map_gfn(struct kvm *kvm, + struct kvm_memslots *slots, gfn_t gfn, struct kvm_host_map *map, struct gfn_to_pfn_cache *cache, bool atomic) @@ -2361,20 +2370,22 @@ static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn, map->pfn = pfn; map->gfn = gfn; + kvm_arch_write_gfn_begin(kvm, slot, map->gfn); + return 0; } int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map, struct gfn_to_pfn_cache *cache, bool atomic) { - return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map, + return __kvm_map_gfn(vcpu->kvm, kvm_memslots(vcpu->kvm), gfn, map, cache, atomic); } EXPORT_SYMBOL_GPL(kvm_map_gfn); int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map) { - return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map, + return __kvm_map_gfn(vcpu->kvm, kvm_vcpu_memslots(vcpu), gfn, map, NULL, false); } EXPORT_SYMBOL_GPL(kvm_vcpu_map); @@ -2412,6 +2423,8 @@ static void __kvm_unmap_gfn(struct kvm *kvm, else kvm_release_pfn(map->pfn, dirty, NULL); + kvm_arch_write_gfn_end(kvm, memslot, map->gfn); + map->hva = NULL; map->page = NULL; } @@ -2612,7 +2625,9 @@ static int __kvm_write_guest_page(struct kvm *kvm, addr = gfn_to_hva_memslot(memslot, gfn); if (kvm_is_error_hva(addr)) return -EFAULT; + kvm_arch_write_gfn_begin(kvm, memslot, gfn); r = __copy_to_user((void __user *)addr + offset, data, len); + kvm_arch_write_gfn_end(kvm, memslot, gfn); if (r) return -EFAULT; mark_page_dirty_in_slot(kvm, memslot, gfn);